Features of the invention relate generally to server performance improvements and, more particularly, to performance improvements based on elimination of repeated processing.
A server receiving numerous requests for resources within a brief period of time must be highly efficient in generating responses if the server is going to fulfill the requests within an acceptable period of time. One illustrative context where this problem arises is in connection with Enhanced Television (xe2x80x9cETVxe2x80x9d). In the ETV context, typically a video production is distributed to numerous client applications. The video production has associated with it one or more enhancing resources that may be selected by a viewer of the video production. Conventionally, the enhancing resources are made available to the viewer by including an identifier of the resource in the video production. The viewer""s client platform, e.g., a set-top box or computer, extracts the resource identifier and provides an indication to the viewer that enhancing resources are available. If the viewer selects the resource, a request is sent with the client application resident in the viewer""s client platform. Frequently in the ETV context, numerous client applications each send requests contemporaneously. This aspect is typically present when, for instance, the video production is broadcast and each viewer becomes aware of the availability of the enhancing resource from the broadcast video production virtually simultaneously. It would thus be desirable for operators of servers receiving numerous simultaneous requests for server efficiency to be improved.
Unfortunately, conventional servers are not highly efficient. For instance, when a conventional HTTP server, receives a request for a uniform resource identifier (xe2x80x98URIxe2x80x99) it first parses the request, then parses header lines in the request. Next, the HTTP server applies a rewrite mapping process that transforms an external name for the resource (in the URI) to an internal name used for locating the resource and generating the response. Conventional modules for performing the rewrite mapping are powerful and flexible, but obtain this power and flexibility only through computational expense. After the HTTP server derives an internal name of the resource it must generate the response (by retrieving the associated file and/or running executable code) as well as generating headers for the response. If a request for the same resource, were to arrive at the server an instant later, a conventional server would repeat the foregoing steps. In a context where there are numerous simultaneous requests for the same set of resources, conventional server processing is needlessly redundant and inefficient.
Another type of conventional server is a caching proxy server. A caching proxy server is a conventional server which stores locally (or at least more locally) to a client certain resources that are requested from hosts on a data network, typically the internet. In this way a caching proxy server reduces response time by reducing or eliminating time lags introduced by having to retrieve the resource from a remote host, that may only be available through a slow or congested network connection. However, the caching proxy server does not reduce that component of total response time that is attributable to processing at the sever; a conventional caching proxy must flow through all of the intermediate states as any other server in generating a response. For example, a caching proxy server retains the inefficiencies of a conventional HTTP server in redundantly performing the mapping from an external name to an internal name for repeatedly-requested resources. Indeed, where delays in response time are introduced not from network lags, but from the sheer request volume at the server, a caching proxy server may provide no noticeable benefits to the user whatsoever.
Accordingly, it would be desirable for there to be a means for reducing redundant processing in serving repeated requests for a resource.
In order to provide these and other objectives, one aspect of the present invention are methods for efficiently generating responses for repeated resource requests. An exemplary method includes: receiving a first request for a first resource; deriving intermediate state information used in generating a first response to the first request and caching the intermediate state information. Then when a second request is received, retrieving the intermediate state information; and generating a second response to the second request using the intermediate state information. Illustrative examples of what the intermediate state information may comprise include: an internal name corresponding to the first resource and a type of the first resource; the first resource; or a plurality of response header lines for the first resource.
Another aspect of the present invention are apparatuses, such as programmed computing hardware, configured for efficiently generating responses for repeated resource requests. An exemplary apparatus includes: a request receiver configured for receiving a first request for a first resource; a request handler configured for deriving intermediate state information used in generating a first response to the first request; a cache storing the intermediate state information; and a request handler configured for retrieving the intermediate state information and further configured for generating a second response to the second request using the intermediate state information. This apparatus may operate, for instance, with similar types of intermediate state information as the forgoing methods.
A still further illustrative method includes: receiving a first request for a first resource, the first request comprising a resource identifier and request modifying information; determining whether generating a response for the first request requires parsing the request modifying information; and, if not, generating the response without parsing the request modifying information. An illustrative apparatus includes: a request receiver configured for receiving a first request for a first resource, the first request comprising a resource identifier and request modifying information; a response generator configured for generating a response to the first request and further configured for determining whether generating the response requires parsing the request modifying information; and a request modifying information parser configured to parse request modifying information only when the response generator determines generating the response requires parsing the request modifying information.
Yet another aspect of the present invention are computer programs products comprising a computer-readable medium having computer readable instructions encoded thereon for efficient server response generation using intermediate state caching. The computer-readable instructions are able to configure computing machinery to carrying on methods in accordance with the invention, or to configure an apparatus in accordance with the invention. So configured, computing machinery provides structural elements for performing functions in accordance with the invention.
In accordance with the forgoing, a summary of an illustrative embodiment may be provided: an HTTP server is modified to carry out the invention; when an HTTP Request Message (comprising a URI) arrives, the server determines if a URI descriptor has already been cached. If not, one is generated. If the request is for a small, plain file, the file and response headers are cached and read out to generate the response. If the response is for an executable, the headers in the Request Message are parsed and the executable generates the response. When a second request arrives for the resource, the server can consult and locate the cached URI descriptor and read out the cached response headers and body. As will be appreciated with reference to the detailed description, illustrative embodiments of the invention obtain efficiencies such as, but not limited to: eliminating parsing of headers in requests until necessary and then only parsing the required headers; caching the costly mapping between an external and internal name for a resource and eliminating redundant processing in repeated requests; caching response headers and body and eliminating redundant processing in repeated requests.